The present disclosure relates to techniques for performing oilfield operations. More particularly, the present disclosure relates to techniques for performing wellbore stimulation operations, such as perforating, injecting, treating, and/or fracturing subterranean formations.
Oilfield operations may be performed to locate and gather valuable downhole fluids, such as hydrocarbons. Oilfield operations may include, for example, surveying, drilling, downhole evaluation, completion, production, stimulation, and oilfield analysis. Surveying may involve seismic surveying using, for example, a seismic truck to send and receive downhole signals.
Drilling may involve advancing a downhole tool into the earth to form a wellbore. The wellbore may be drilled along a vertical, angled or horizontal path. Downhole evaluation may involve deploying a downhole tool into the wellbore to take downhole measurements and/or to retrieve downhole samples. Completion may involve cementing and casing a wellbore in preparation for production. Production may involve deploying production tubing into the wellbore for transporting fluids from a reservoir to the surface.
Wells may be drilled along a desired trajectory to reach subsurface formations. The trajectory may be defined to facilitate passage through subsurface formations and to facilitate production. The selected trajectory may have vertical, angled and/or horizontal portions. The trajectory may be selected based on, for example, vertical and/or horizontal stresses of the formation. These stresses may be far-field stresses that result from stress applied away from the wellbore due to, for example, geological structures, such as tectonic plates.
Perforations may be performed in cased wells in order to make it possible for reservoir fluids to flow into the well. Perforations may be formed using various techniques to cut through casing, cement and/or surrounding rock. Stimulation operations, such as acid treatments and hydraulic fracturing, may also be performed to facilitate production of fluids from subsurface reservoirs.
Natural fracture networks extending through the formation also provide pathways for the flow of fluid. Man-made fractures may be created and/or natural fractures expanded to increase flow paths by injecting treatment into the formation surrounding the wellbore. Fracturing may be affected by various factors relating to the wellbore, such as the presence of casing and cement in a wellbore, open-hole completions, spacing for fracturing and/or injection, etc. Examples of fracturing are provided in U.S. Pat. No. 7,828,063.